Various digital techniques have been used to generate musical sounds. One of the earlier techniques was the sampling of a waveshape stored in a read only memory, disclosed in U.S. Pat. No. 3,515,792. This technique allows a good approximation of a steady state musical sound but lacks flexibility in the attack and decay segments. In addition, for the case where the spectral components of a single instrument vary with frequency, a large number of waveshapes must be stored.
The Fourier component synthesizer overcomes the problems of the waveshape synthesizer by being able to completely specify the spectral components of a sound, disclosed in U.S. Pat. No. 3,809,786. The main drawback to the Fourier component synthesizer is the large number of calculations necessary to generate a single musical sound, e.g., a trompette stop would require at least the generation of 16 harmonic amplitudes.
The technique described in this patent overcomes the approach of a waveshape synthesizer and the Fourier synthesizer by using a collection of eigenvector sets which have been generated from a related group of sounds. A group may be either a sound of a single instrument over its total frequency range and its attack and decay or several instruments with similar harmonic characteristics.